Add history command (#643)

* Add history command

* Sort the imports in history.py

* Add history command to docs

docs/source/commands/history.rst

@@ -0,0 +1,2 @@
+.. autoprogram:: pwndbg.commands.history:parser
+   :prog: history

pwndbg/__init__.py

@@ -30,6 +30,7 @@ import pwndbg.commands.gdbinit
 import pwndbg.commands.got
 import pwndbg.commands.heap
 import pwndbg.commands.hexdump
+import pwndbg.commands.history
 import pwndbg.commands.ida
 import pwndbg.commands.leakfind
 import pwndbg.commands.misc

pwndbg/commands/__init__.py

@@ -81,6 +81,8 @@ class Command(gdb.Command):
         """Invoke the command with an argument string"""
         try:
             args, kwargs = self.split_args(argument)
+            # skip all None kwargs so we don't have to pass default values twice in argparse and function
+            kwargs = {k: v for k, v in kwargs.items() if v is not None}
         except SystemExit:
             # Raised when the usage is printed by an ArgparsedCommand
             return

pwndbg/commands/history.py

@@ -0,0 +1,28 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+"""
+Display the history.
+"""
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+from __future__ import unicode_literals
+
+import argparse
+import readline
+
+import gdb
+
+import pwndbg.commands
+
+parser = argparse.ArgumentParser()
+parser.description = __doc__
+parser.add_argument('count', type=int, nargs='?',
+                    help='The amount of history entries to display')
+@pwndbg.commands.ArgparsedCommand(parser)
+def history(count=10):
+    history_length = readline.get_current_history_length()
+    history = reversed([readline.get_history_item(i) for i in range(history_length)])
+    history = list(history)[:min(count, history_length)]
+    for entry in history:
+        print(entry)